时间:2019-01-22 作者:英语课 分类:英语时差8,16


英语课

 Fact: liquid water is heavier than air. Fact: clouds, which consist of water droplets 2 and ice crystals, seem to hover 3 in the air. One final fact: the water droplets in a typical cloud together weigh many tons. Which raises a question: how do clouds stay up in the sky?  Clouds form when warm, moist air rises to a greater altitude, causing it to expand and cool. Eventually, water vapor 4 in the cooled air condenses into the droplets that form clouds. The condensed droplets are on average roughly eight-one-hundred- thousandth of an inch across. In other words, a single droplet 1 is very, very small.


Despite their tiny size, the droplets still have mass and are therefore affected 5 by gravity. They are so small, however, that rising air keeps the water droplets aloft. The effect is similar to how dust appears to float in a shaft 6 of sunlight: although gravity works on the bits of dust, even the gentlest currents are enough to keep them swirling 7 around in the air.
Clouds, then, are not so much able to float as they are held up by surrounding air. In fact, the tiny cloud droplets do sink, but so slowly that it would take an hour for a single droplet to sink only one yard. And although the cumulative 8 weight of a cloud's droplets is many times that of the surrounding air, the droplets are spread out over a large enough area to render the gravitational pull on any single drop almost negligible. When the droplets become larger, gravity overcomes the dragging forces of the rising air and the droplets fall to the earth as rain.   

n.小滴,飞沫
  • The rate of droplet growth under different conditions can be evaluated.可以计算在不同条件下的云滴增长率。
  • The test results showed that increasing droplet size was associated with better stability.试验结果表明,增加液滴尺寸将使稳定性提高。
n.小滴( droplet的名词复数 )
  • Droplets of sweat were welling up on his forehead. 他额头上冒出了滴滴汗珠。 来自辞典例句
  • In constrast, exhaled smoke contains relatively large water droplets and appears white. 相反,从人嘴里呼出的烟则包含相当大的水滴,所以呈白色。 来自辞典例句
vi.翱翔,盘旋;徘徊;彷徨,犹豫
  • You don't hover round the table.你不要围着桌子走来走去。
  • A plane is hover on our house.有一架飞机在我们的房子上盘旋。
n.蒸汽,雾气
  • The cold wind condenses vapor into rain.冷风使水蒸气凝结成雨。
  • This new machine sometimes transpires a lot of hot vapor.这部机器有时排出大量的热气。
adj.不自然的,假装的
  • She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
  • His manners are affected.他的态度不自然。
n.(工具的)柄,杆状物
  • He was wounded by a shaft.他被箭击中受伤。
  • This is the shaft of a steam engine.这是一个蒸汽机主轴。
v.旋转,打旋( swirl的现在分词 )
  • Snowflakes were swirling in the air. 天空飘洒着雪花。 来自《现代汉英综合大词典》
  • She smiled, swirling the wine in her glass. 她微笑着,旋动着杯子里的葡萄酒。 来自辞典例句
adj.累积的,渐增的
  • This drug has a cumulative effect.这种药有渐增的效力。
  • The benefits from eating fish are cumulative.吃鱼的好处要长期才能显现。
学英语单词
aberrometry
abrotanum
adenomyositis
alaria crassifolia kjellm
allocation strategy module
anderton shearer-loader
Andorf
arab-berber
Artfjeld
ashiko
at the behest of
automatic routine
autophagolysosomes
ball platform scale
bankrupcies
Barkley, Lake
be straight with sb
bleachers
blockader
borrow memory control
cam shaft sprocket
canonical case
chloroserpidine
Choeropotamidae
cock body
cold-sensitive mutant
colors
common peppers
congenital cyst of sublingual gland
conical stiffener
contending passions
control requirement
cramoysen
dediploidization(buller 1941)
doors and windows
drive away at
dumbard
ekiti
fabrication platform
fatty acid activating enzyme
flouncer
flour milling
foundry mould
freestylers
generalized two-phase model
genus botrychiums
Goniothalamus yunnanensis
Hanover County
health-insurance
helicopter land ing gear
heterocarpy
homeware
indifference curve
interfering nuclear reaction
interradial piece
interrogation-inquiry
iron mts.
kalkilya
koevermans
lineae parasternalis
lost ground
magnify oneself against sb.
marching problem
moisture examining instrument
nautical meteorology
newly built
normal reactive force
occult tail
pabulums
Pelagonisou, Diavlos
plan bracing
polyaromatic amide (aramid) pulp reinforcement
put on side
quarantinable diseases
Quercus chingsiensis
rbol
rejiggering
Republic of Moldova
restriction fragment
roll tite hathcover
sctinography
semi-floating axle
serratamolide
share responsibility for
small horse hides
soup-spoon
station pressure
system programmed operator
television relay car
thain
the mode
three-statest
tit fucks
turntabling
uncommerciable
unpieces
veto vacuum unloading gear
virtual O device
voidableness
vriesea carinata
web of Penelope
yakalo